2012 S60 dead battery help

[Brianvs60]

Hey all,

Come home from a weekend away to a car that wouldn't unlock - neighbour reminded me I left my sidelights on since Friday evening. Grr.

I've gained access to the car and to the boot, and I've got a home (4 amp) charger connected to the battery + terminal and to the engine mount (I initially had it to the battery - terminal, hope that hasn't caused more damage)

How long should it be before I can unlock the car and/or try starting it? Should I try get jump cables?

Any advice gratefully received.

[XC90Mk1]

Originally Posted by Brianvs60

Hey all,

Come home from a weekend away to a car that wouldn't unlock - neighbour reminded me I left my sidelights on since Friday evening. Grr.

I've gained access to the car and to the boot, and I've got a home (4 amp) charger connected to the battery + terminal and to the engine mount (I initially had it to the battery - terminal, hope that hasn't caused more damage)

How long should it be before I can unlock the car and/or try starting it? Should I try get jump cables?

Any advice gratefully received.

If you leave it 4 hours then you should be ok to unlock. I would leave it 24 hours to charge up and then start it.

As you probably know once started don’t turn the engine off for less than 15 minutes and really take it for a 15-20
Minute drive ideally.

[Brianvs60]

Yeah hopefully it's just a matter of time.

When I started charging -
The hazard lights flashed a few times;
Interior lights were on dimly for a few minutes;
The red flashing alarm light was flashing rapidly for a few minutes

All of those have stopped now - I presume was just the alarm sorting itself out? Just a waiting game from here on?

[XC90Mk1]

Originally Posted by Brianvs60

Yeah hopefully it's just a matter of time.

When I started charging -
The hazard lights flashed a few times;
Interior lights were on dimly for a few minutes;
The red flashing alarm light was flashing rapidly for a few minutes

All of those have stopped now - I presume was just the alarm sorting itself out? Just a waiting game from here on?

It’s likely to be various modules powering up etc. I would basically leave it now. Overnight will be best. I doubt that you will suffer any issues.

[Tannaton]

With regard to connecting the charger the wrong way - the charger itself will give up long before the car would notice.

[Brianvs60]

Thanks both for your help and reassurance. Not looking great though, not a peep out of the car with the charger on all night, but I had sourced a set of jumper cables and connected them up with the other car in the house.

Left that on for a bit and lo - a glorious moment of happiness, the dash lights up and I can unlock the car.

Tried to start - 2 unhealthy coughs later and we're back in flatland....

Starting to think about recovery - they'll have a better battery booster? Battery might be at end of life - start/stop has been unavailable recently.

[Clan]

Originally Posted by Brianvs60

Hey all,

Come home from a weekend away to a car that wouldn't unlock - neighbour reminded me I left my sidelights on since Friday evening. Grr.

I've gained access to the car and to the boot, and I've got a home (4 amp) charger connected to the battery + terminal and to the engine mount (I initially had it to the battery - terminal, hope that hasn't caused more damage)

How long should it be before I can unlock the car and/or try starting it? Should I try get jump cables?

Any advice gratefully received.

I would leave it 48 continuous hous at least then run the car for a few days and one morning put a voltmeter across the terminals with everything off and see what the voltage is.. 12.7 is good 12.3 is bad...

[glynh]

what is the battery charger saying, and are you using a good quality one suitable for the battery type? does it have any visual aids to show what level of charge the battery is?

if the battery was completely shot then the charger would probably tell you.

I have charged up many a dead battery back to life with a 'smart' charger.

[Tannaton]

I would disconnect the battery negative lead and then try again, connecting the battery charger directly to both battery terminals.

Your 4 amp charger is at the low end of charger ratings and I suspect that the systems in the car that power up for a few seconds and then go to sleep when the battery is connected or doors opened etc. are consuming all of the charge and none going to the battery. So if you connect the charger only to the battery, it will get the full dose. You won't affect the BMS system as this should reset itself when the battery is disconnected for more than a few mins anyway.

If you can, as said above, I'd leave it like that circa 48 hours and try again. You could temporarily reconnect the negative lead after say 4 hours just to see if the battery is taking a charge and it will sustain the basic systems, if it won't after 4 hours then you should inform the battery's next of kin.........

On a 2012 car it's not inconceivable you are still running on the original factory battery in which case you've had your monies worth.

[Brianvs60]

Hi all, thanks for the follow ups.

@Tannaton you hit the nail on the head - original battery @10years of age, discharged to something flatter than a flat-mates flat-head screwdriver in a flat toolbox.

Rescue service came, got the car started alright but all the battery metrics were pointing at imminent replacement so I took the one he had. Probably paid a little premium but it was done and dusted there and then.

Most importantly everything still works but I did have to reset the clock which was a huge chore.

Windows lost one-touch up/down until I wound them all the way down!

Do appreciate all the messages.

Thinking now about one of those power packs - I hope I'll not need it for a while but might be a useful thing to have around.